A novel optical profiler design is described in this paper for measuring surface profiles of synchrotron radiation (SE) mirrors. The measurement is based on the combination of an optical heterodyne technique and precise phase measurement without a reference surface. A Zeeman 2-frequency He-Ne laser is employed as the light source. The common-path optical system which uses a biref ringent lens as the beam splitter makes it possible to minimize the effects due to air turbulence, sample vibration and temperature fluctuation. The profiler can be used to measure the roughness and curvature of a sample surface based on a special autofocus system. The optical system is mounted on a large linear air-bearing slide, and is capable of scanning over distances covering the spatial measurable period range from several microns to nearly one meter with a very high measuring accuracy.